GLAPI/glReadBuffer

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glReadBuffer
Core in version 4.4
Core since version 1.0

glReadBuffer: select a color buffer source for pixel read operations from the current read framebuffer.

Function Definition

 void glReadBuffer(GLenum mode​);
mode
Specifies a color buffer. Accepted values are GL_FRONT_LEFT​, GL_FRONT_RIGHT​, GL_BACK_LEFT​, GL_BACK_RIGHT​, GL_FRONT​, GL_BACK​, GL_LEFT​, GL_RIGHT​, and the constants GL_COLOR_ATTACHMENTi.

Description

glReadBuffer specifies which color buffer within the current bound GL_READ_FRAMEBUFFER​ will be used as the source for pixel reading commands. These commands include: glBlitFramebuffer, glReadPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, and glCopyTexSubImage3D.

mode​ accepts one of twelve or more predefined values. If the Default Framebuffer (the zero Framebuffer Object)is bound to GL_READ_FRAMEBUFFER​, then the following enumerators can be used: GL_FRONT​, GL_LEFT​, and GL_FRONT_LEFT​ all name the front left buffer, GL_FRONT_RIGHT​ and GL_RIGHT​ name the front right buffer, and GL_BACK_LEFT​ and GL_BACK​ name the back left buffer. Nonstereo double-buffered configurations have only a front left and a back left buffer. Single-buffered configurations have a front left and a front right buffer if stereo, and only a front left buffer if nonstereo.

If a non-zero framebuffer object is bound, then the constants GL_COLOR_ATTACHMENTi may be used to indicate the ith color attachment, where i ranges from zero to the value of GL_MAX_COLOR_ATTACHMENTS​ minus one.

It is an error to specify a nonexistent buffer to glReadBuffer.

For the default framebuffer, mode​ is initially GL_FRONT​ in single-buffered configurations and GL_BACK​ in double-buffered configurations. For framebuffer objects, the default read buffer is GL_COLOR_ATTACHMENT0​.

Errors

GL_INVALID_ENUM​ is generated if mode​ is not one of the twelve (or more) accepted values.

GL_INVALID_OPERATION​ is generated if mode​ specifies a buffer that does not exist.

Associated Gets

glGet with argument GL_READ_BUFFER​

See Also

glBindFramebuffer, glDrawBuffer, glDrawBuffers, glReadPixels

Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2011 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.